Fast ice flow on the Antarctic continent constitutes much of the mass loss from the ice sheet. However, geophysical methods struggle to constrain ice flow history at depth, or separate the signatures of topography, ice dynamics and basal conditions on layer structure. We develop and demonstrate a methodology to compare layer signatures in multiple airborne radar transects in order to characterize ice flow at depth, or improve coverage of existing radar surveys. We apply this technique to generate synthetic, along-flow radargrams and compare different deformation regimes to observed radargram structure. Specifically, we investigate flow around the central sticky spot of Whillans Ice Stream, West Antarctica. Our study suggests that present-day velocity flowlines are insufficient to characterize flow at depth as expressed in layer geometry, and streaklines provide a better characterization of flow around a basal sticky spot. For Whillans Ice Stream, this suggests that ice flow wraps around the central sticky spot, supported by idealized flow simulations. While tracking isochrone translation and rotation across survey lines is complex, we demonstrate that our approach to combine radargram interpretation and modeling can reveal critical details of past ice flow.

中文翻译：

---

用合成雷达图解释存在复杂冰流历史的冰层变形

南极大陆上的快速冰流构成了冰盖的大部分质量损失。然而，地球物理方法难以限制深度的冰流历史，或分离地形、冰动力学和层结构基础条件的特征。我们开发并演示了一种方法来比较多个机载雷达横断面中的层特征，以便表征深度的冰流，或改善现有雷达调查的覆盖范围。我们应用这种技术来生成合成的顺流雷达图，并将不同的变形状态与观察到的雷达图结构进行比较。具体来说，我们调查了南极洲西部惠兰斯冰流中心粘性点周围的流动。我们的研究表明，目前的速度流线不足以表征深度流动，如层几何所示，和条纹可以更好地表征基础粘性点周围的流动。对于 Whillans Ice Stream，这表明冰流环绕中心粘性点，由理想化的流动模拟支持。虽然跨测量线跟踪等时平移和旋转很复杂，但我们证明了我们结合雷达图解释和建模的方法可以揭示过去冰流的关键细节。